The second smallest eigenvalue \(\lambda _2\)  of a Laplacian \(L_n\)  is known as the algebraic connectivity of the related graph of \(n\)  agents, and the corresponding vector is known as the Fiedler vector [1]} . This eigenvalue provides a quantitative measure of the global communication strength of a multi-agent system. A multi-agent graph with positive \(\lambda _2\)  has at least one spanning tree ensuring an information flow path among agents, whereas with null \(\lambda _2\)  there exists no spanning tree and so the information exchange gets interrupted. A higher value of \(\lambda _2\)  indicates more connections among agents, which is useful in cooperative missions like multi-agent tracking [2]} and formation control [3]} for maintaining, improving or controlling time-varying connectivity during the dynamics.
